Quality and consistency for whole-building LCAs using product-specific EPDs

Quality and consistency for whole-building LCAs using product-specific EPDs

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When you evaluate the life-cycle performance of your building, using the datapoints from manufacturers and products in your evaluation will achieve a more accurate result than using average data.

Products in the same product category can differ in their environmental impacts with several multiples. This makes it paramount that the real product is used for assessment when data is available. This position paper article explains how One Click LCA achieves that with EPDs while ensuring robust and comparable results.


Using real data to make real decisions is paramount

When you are trying to optimize your project’s environmental impacts, what you specify is a very powerful lever. For example, ready-mix concrete for external walls and floors embodied carbon per cubic meter ranges from below 200 kg CO2e to above 500 kg CO2e for manufacturing in the U.S. In case of metal-based products, the embodied carbon ranges are even wider. Between similar products, one manufacturer’s greener manufacturing or supply process can give their product a substantial reduction in carbon and LCA emissions. When you specify products for your project and evaluate their performance using Whole-Building Life-Cycle Assessment (e.g. for LEED v4 LCA credits), using the real data for the assessment is paramount. If you do not use manufacturer data (e.g. EPDs), your LCA will treat a manufacturer using recycled materials, energy-saving materials and green energy supply same as another with virgin materials, conventional equipment, and a fossil fuel-based energy supply the same. This will greatly harm the accuracy of the LCA study, as well as the environment if better suppliers are not preferred. The flexibility of being able to use actual manufacturer data also allows reducing the project’s environmental impacts even in the specification and sourcing phase. One Click LCA database contains over 10 000 construction materials environmental impact profiles, and it’s constantly being enriched with new, qualified data from our LCA database engineers. 

If you have a subscription to One Click LCA, you can send new LCA data that you want to use, e.g. a new EPD fresh out from a manufacturer you work with to our support team. This data will go through the entire verification process and if it passes, it becomes available as outlined in this document.

Comparability of Building LCA results


Comparability for a Life Cycle Assessment results requires a few things: comparable scope, comparable life-cycle phases for all compared options and technically comparable calculation data and assumptions. On top of this, the data, the scope and the results of the study must be fit for their purpose, for example, to qualify for Whole-Building Life-Cycle Assessment for LEED v4 credits. This article explains how these issues can be tackled to ensure robust, high quality and consistent LCA results for construction works, and in particular, how One Click LCA manages this. One Click LCA ensures this by checking all available LCA data rigorously to ensure they comply with LEED v4 and other requirements (see next chapter). Further, data is set up with corresponding life-cycle models.

Managing materials LCA data quality and consistency – The groundwork

Globally, there are well over 30 EPD programs and numerous LCA and carbon databases. These vary in a number of respects, especially in terms of mandatory reported life-cycle stages and in the definition of the life-cycle scenarios applied to those. For EPD programs, these parameters are defined in Product Category Rules. Some programs only report manufacturing impacts, whereas others report a more complete picture of the product life-cycle. Programs may also vary in other regards, for instance in requiring the use of regional characterization methods for the LCA. To be sure, there are EPDs that do not meet our standards of quality. Those EPDs typically fulfill only the ISO 14040, ISO 14044 and ISO 14025 standards. Most of those EPDs have been published prior to or very soon after the publication of EN 15804 or the more recent ISO 21930, which are the most commonly applied modern EPD standards. One Click LCA policy for such EPDs is a simple one: we do not include those data. One Click LCA’s LCA database engineering team integrate all building materials LCA data that a) is technically and scientifically valid, b) verified by a third-party, or verifiable by us, c) is useful for building LCA end users, and d) is openly available. Data that does not meet these criteria are excluded. We use a 10-point verification method to go through a new data source. (more on this in the chapter below). This is a pass or fail process. Some data sources do not qualify at all at a source level, in such cases, the process stops here. In the case of a pass, we create a set of descriptive metadata to enrich the value of the data, for example, adding technical characteristics to the data. 
In One Click LCA you can always see the background information of any datapoint you use, including what standards it complies with, what PCR it applies and so forth. All EPDs in the platform are third-party verified. You also can download the EPDs and review the information available in it directly.

Third-party verified methodology for checking data quality in detail

We have built in our data processing and verification tools over 50 checking tools, which perform several hundreds of checks on all new data. We perform extensive data verification with our experienced in-house LCA database team. One Click LCA’s data verification methodology has been third-party reviewed by Building Research Establishment (BRE). The detailed verification methodology is our intellectual property. It covers all requirements in the LEED v4 manual for Incorporation of EPD data in WBLCA Tools, namely:

Requirement for using EPDs Approach
Has not expired. One Click LCA does not allow choosing expired data. If you start using a datapoint when it’s still valid, it will not be removed from the projects where is used on expiry, it simply can’t be added as a new datapoint anywhere any longer.
EPD scenarios should be representative of contemporary technologies and/or practice, and the project location. We ensure this in our verification process and when setting products in a relevant data domain.
Reports all indicators and system boundary information modules required by the WBLCA tool. Data exclusion criteria. Minimum scope for life-cycle phases is cradle to gate (A1-A3). Additional stages for the life-cycle model are enabled in accordance with regional practices and patterns.
Characterizes the impact categories reported according to the same LCIA methodology as the WBLCA tool. Data exclusion criteria.
Can be applied to the study period of the assessment. Data exclusion criteria.
Clearly indicates which product (including manufacturer and product name) or geographical region it reflects in comparison to the industry-wide weighted average results of a material or fuel already available in the tool. This metadata is made available when a datapoint included in One Click LCA. The industry average product performance is available via benchmarks.


Once a datapoint is qualified, classified, and verified, it’s released to users until expiry or withdrawal in the appropriate regional data domain (see below).

The product drives manufacturing impacts, the building the other life-cycle impacts

The LEED v4 manual states that Additionally, comparability shall be ensured in accordance with Section 5 of the BRE Briefing Paper “Assessing the environmental impacts of construction – understanding European Standards and their implications. The mentioned section defines life-cycle modeling implications exactly as One Click LCA implements them. These are shown in the table below, after the example. Consider, for example, glass wool. A manufacturer makes the product and publishes EPDs. When the product is sold, the manufacturing impacts are the actual impacts reported by the manufacturer in the verified EPD. However, the end of life impacts of the same product will be different based on the location where the building is built, as that is the region where it will be disposed of. Our modeling practice ensures this is taken to account.  

Life-cycle module EN 15978/ISO 21930 Influenced by (BRE paper) Included in LEED v4 LCA Implementation in One Click LCA based on
A1 Raw material supply A2 Transport of the materials A3 Manufacturing Product X Material datapoint
A4 Transport to construction site Building X User given distance and transport method OR user-confirmed region defaults
A5 Construction, Installation Building User-given data or user-selected default
B1 Use B2 Maintenance B3 Repair Building X Via data domain defaults or material specific datapoints
B4 Replacement B5 Refurbishment Building X Via service life either set by the end user or user-confirmed defaults
B6 Operational energy Building User given inputs
B7 Operational water Building User given inputs
C1 Deconstruction, demolition Building X Regional scenario
C2 Transport of wastes/ demolition material Building X Regional scenario
C3 Waste processing Building X Material properties and regional scenario
C4 Disposal Product X Material properties and regional scenario
D Reuse, recovery, recycling Product/Building Material properties (e.g. energy content) and regional scenario

The above life-cycle model is following EN 15978 and ISO 21930. One Click LCA’s compliance with both mentioned standards has been verified by an accredited body: EN 15978 and ISO 21930. The approach also allows full compliance with E2921 – 16a: Standard Practice for Minimum Criteria for Comparing Whole Building Life Cycle Assessments for Use with Building Codes, Standards, and Rating Systems.

All data visible and reported transparently

 In One Click LCA, the data you work with is visible in your user interface (Business/Expert subscriptions). You can see the metadata associated with a datapoint and have direct download access to the EPD or comparable source right from your user interface. Result breakdowns are also transparently available for a detailed analysis. With the Expert level license, you can also access Green Materials benchmarks to help you identify attractive suppliers and solutions for your needs.


You can also filter the data according to your preferences, so you can choose to work e.g. with generic datapoints, only Ecoinvent-based datapoints, and prefer any data sources you like over others. You can search data using categories or free-text search, as you prefer.


Choose the data that represents your project best by using filters

If a material you aim to use in One Click LCA has unusual properties, One Click LCA provides a notice to inform you of this, to be sure you do not choose an unconventional material accidentally. This may apply for example to screeds that are mixed with an epoxy resin.

One Click LCA groups all data into consistent and comparable data domains

We group LCA data into a number of regional data domains. An end user of any single LCA tool on One Click LCA platform will only ever use data from one of the data domains at once. This ensures that an end user can’t use data that is not suited for the purpose, or incomparable with other data. When we release data, we also enable a consistent and realistic life-cycle model for the data that is representative of the product as well as the region where it is used. This ensures all comparable products in the data domain will have comparable and consistent behavior when used in building LCA, also when the manufacturer only provided manufacturing impacts.  

Data domain examples Identified by Examples
North American data TRACI 2.1-compliant, ISO 14044-compliant, includes all six LEED LCA impact categories and minimum life-cycle stages One Click LCA generic data and North American EPDs
European data CML-compliant, ISO 14044-compliant, includes all six LEED LCA impact categories and minimum life-cycle stages One Click LCA generic data and European EPDs
National/regulatory data (several different domains) Regulatory requirements or mandated LCA data/properties Nationale Milieudatabaase (Netherlands) Nationale Milieudatabaase (Netherlands)

Customer private data is also incorporated into the data domains – this is the case that applies, for example, if you create your own concrete mixes or specific constructions. This data is always part of the data domain which you are using in your day to day work.

One Click LCA supports 30+ different building and construction works LCA models

The One Click LCA platform is tool-driven. For example, there’s one LCA tool for LEED v4 for the United States, one for Canada, one for Europe and for international use. Each tool enforces all aspects required for comparability of results for the stated purpose. The tools also defined the reporting templates according to the requirements of the targeted system. Some of the commonly used tools on the platform include:

This approach means that you can use One Click LCA for your LCA requirements anywhere in the world without having to compromise on compliance or local representativeness.

Accounting locally made products accurately

For most geographies, you will not find environmental data to represent locally made products for all manufacturers you work with. In such cases, you’ll want to use generic LCA data for those products. Manufacturing processes use various forms of energy. By and large, fuel-using processes tend to be the same across countries and regions, but the electricity grid-mix used in manufacturing varies. If you buy a locally-made product just across the state border from a state using more emissions-intensive electricity, your product impacts are likely to be correspondingly higher. One Click LCA supports local compensation of product manufacturing to all countries in the world as well as US states, Canadian provinces and territories and soon also Australian states and territories. One Click LCA local compensation methodology is a peer-reviewed methodology implementing the guideline from CEN/TR 15941 for making product data locally adaptable. The methodology considers also waste handling processes as well as energy performance differences between regions. Activating the use of local compensation is always confirmed by the end user. Use of local compensation makes overall building impacts more representative of the local context in the case when products are also mostly locally made.

Summary: getting quality right every time, wherever you work

  Performing whole-building LCAs requires accurate, comparable and consistent data. One Click LCA’s unique approach ensures that when you pick a tool for a specific analysis, e.g. LEED v4 LCA, the requirements are always met. And moreover, since you can use specific product information as well as LCA data representing local manufacturing, you’ll know your results are as accurate and provide a sound basis besides design choices, also for specification and procurement decisions. We will be happy to receive any questions or comments at  




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